1. Technical Field
The present invention relates to a method and apparatus for evaluating video quality, more particularly to a technique for objectively evaluating a video sequence that has a reduced resolution compared to an original video sequence and a multi-resolution video quality evaluation technique.
2. Description of the Related Art
The technology of evaluating video quality is ever growing in importance, especially in view of its critical role in fields relating to verifying the performances of video codecs and developing new compression coding techniques as well as evaluating video transmission quality, and the like.
Until now, evaluating video quality entailed a plurality of evaluators providing their own subjective opinions. This method, however, is very inefficient, being greatly limited in terms of time and cost, and having an additional drawback in that real time evaluation is not possible.
In particular, due to advances in digital technology and communications technology, techniques have been developed that allow digitalizing video sequences and transmitting the images over a network. In systems for transmitting encoded images based on such digital techniques, it is important to monitor the video quality at the receiving device.
Conventional video transmission systems were developed with the assumption that the original video sequence transmitted from the transmitting device and the processed video sequence received at the receiving device have the same resolution. However, due to problems in the network environment, etc., cable and Internet multimedia services often use a method of reducing the screen of the original video sequence for transmission and restoring the screen of the original video sequence for output when the video sequence is played.
For example, an original video sequence having a resolution of 1080 lines may be reduced to a 720 line resolution and encoded by a transmitting device when the video sequence is transmitted to a receiving device, and after the receiving device receives and decodes the video sequence, it may be converted back to the resolution of the original video sequence (1080 pixels) when it is displayed.
With this existing method, however, it may be difficult to accurately predict the video quality perceived by the viewer at the receiving device.